1. Technical Field
The present disclosure generally relates to mufflers and vehicle exhaust systems for quieting combustion chamber noise.
2. Description of the Related Art
Many known combustion engines utilize expanding high-pressure combustion gasses to move a piston. Ignition of the fuel creates high-pressure pulses of combustion gasses that exit the engine manifold and travel down pipes to a muffler that helps reduce the noise from the engine. When the combustion gasses, also referred to herein as the exhaust gasses or exhaust gas, exit the tailpipe of a vehicle engine noises are heard. The rapid pressurization and subsequent depressurization of the exhaust system caused by the high-pressure pulses create a loud sound. As would be expected, the louder the noise, the more significant the annoyance factor and more potential damage to hearing.
The use of mufflers with combustion engines to reduce the amplitude of the acoustic energy of the exhausting gas is known. A typical muffler is located along an exhaust pipe and provides a large expansion volume compared to the pipe. With the muffler in place, the pressurized combustion gasses have a relatively large volume into which to expand. As the combustion gasses expand into the volume of the muffler, the pressure of those gasses falls significantly. Therefore, as the exhausting gas finally exits the muffler, the pressure of the combustion gasses being released to the atmosphere is significantly lower than the pressure of the combustion gasses when a muffler is not used. By reducing the peak amplitude of the combustion gas pressure released to the atmosphere, the sound of the vehicle exhaust system is much softer.
Many existing mufflers are typically of complex construction. For example, many mufflers have small orifices or diffusion materials that may become fouled by residue deposited as combustion gasses pass through the muffler. Fouling of these parts and variances during the life of the vehicle exhaust system may cause reduced efficiency and/or total inoperability of the muffler. Many existing mufflers also require the use of baffling materials for the reduction of the exhaust noise.